Those are two different species of Hibiscus, Lynn, so that one isn't a duplicate.

The Brassica entries can't be duplicates. One is a cabbage and the other is broccoli.

There are two different cultivars of Narcissus named 'Horizon.' There's usually a comment by jmorth to say so, and there is one on the page for the second 'Horizon,' but I suppose he should have added a pertinent comment to the first entry as well.

I don't know about the lilies. Check with the monitor for that section of the database.

Different divisions (13) of Narcissus (type of bloom) or color of bloom (designated by capital letters), or sometimes breeder, sometimes registration (or not).
(Sand & Sea 2 wrote up a nice bit on the divisions on the Narcissus homepage in database) Daffodils (Narcissus)